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International Journal of Antennas and Propagation
Volume 2015 (2015), Article ID 989517, 11 pages
Research Article

Joint Phased-MIMO and Nested-Array Beamforming for Increased Degrees-of-Freedom

School of Communication and Information Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China

Received 18 June 2014; Revised 7 December 2014; Accepted 18 January 2015

Academic Editor: Hang Hu

Copyright © 2015 Chenglong Zhu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Phased-multiple-input multiple-output (phased-MIMO) enjoys the advantages of MIMO virtual array and phased-array directional gain, but it gets the directional gain at a cost of reduced degrees-of-freedom (DOFs). To compensate the DOF loss, this paper proposes a joint phased-array and nested-array beamforming based on the difference coarray processing and spatial smoothing. The essence is to use a nested-array in the receiver and then fully exploit the second order statistic of the received data. In doing so, the array system offers more DOFs which means more sources can be resolved. The direction-of-arrival (DOA) estimation performance of the proposed method is evaluated by examining the root-mean-square error. Simulation results show the proposed method has significant superiorities to the existing phased-MIMO.